A known fluid ejection apparatus includes an inkjet head having an ink inflow passage, an ink tank for storing ink therein, and an ink supply tube having an ink passage. Ink is supplied from the ink tank to the inkjet head through an ink supply passage which includes the ink passage of the ink supply tube and the ink inflow passage of the inkjet head. Air in the ink supply passage grows in volume with time, which may degrade ejection characteristics of the inkjet head. The volume of ink in the ink supply passage is calculated based on a time elapsed from a reference time, and purging is executed, based on the calculated volume of air, to discharge air together with ink from the ink supply passage.